Recently, by development of program executive environment Java (Ken Arnold, James Gosling, “The Java Programming Language, Second Edition,”) independent from a platform, a system to cooperate various kinds of information equipments with Java is greatly taken into consideration. In case of implementing a distributed application by Java, in general, a communication mechanism, “Remote Method Invocation (RMI)”, is utilized as communication means (Troy Bryan Downing, “RMI: Developing Distributed Java Applications with Remote Method Invocation and Serialization,” IDG Books World Wide, Inc. 1998). RMI is an extended version of method invocation mechanism between objects in Java. RMI is a simple and powerful communication mechanism that conceals a complicated communication processing. However, Java and RMI cannot adjust to a change in the IP address (Hereinafter, called “network address”) of the executive computer (host). The following two problems then arise.
(1) When a client connects to a server, in RMI, the connection is executed using information “remote reference”. The remote reference includes the network address (IP address) and a port number of the computer executing a server program. For example, when the computer is activated (power is turned on) and the service is disclosed, the server program creates the remote reference. In this case, the network address at the creating time is written in the remote reference. If the network address is changed, a mechanism to update the remote reference is not prepared. Accordingly, after the network address changes because the computer moved, the remote reference distributed by the server program (to register to a directory service program) includes the network address before the computer moved. After a client program receives this remote reference, the client program tries to connect to the server using the old network address. The client program cannot connect to the server having the new network address.
(2) In the RMI, a Java object is sent and received between the server and the client. In the Java program receiving side, a class file corresponding to received Java object is necessary. If the Java program already has the class file, the Java program executes processing of received Java object using the class file. However, if the Java program does not have the class file, the Java program refers to information of supply source of the class file annotated to the Java object, and downloads the class file from the supply source. After that, the Java program executes processing of the Java object. The information of supply source of class file annotated to the Java object is called “codebase”. The codebase is indicated by Uniform Resource Locator (URL) format. In the same way as the remote reference, the codebase is static, and the codebase does not have an update mechanism in cooperation with a change of the network address. Accordingly, if a computer whose network address dynamically changes such as network moving is the supply source of a class file (in case that HTTP server is executed on a server machine), the codebase is not updated and a program at the receiving side cannot normally operate.